The present invention includes a fungicidal composition comprising a fungicidally acceptable carrier and/or surface active agent and synergistically effective amounts of at least one compound of formula I, and at least one N-pyridylaniline compound.
Fungicidal N-pyridylaniline compounds are known for example from EP 0 031 257. The International patent application WO 95/04460 suggest to prepare fungicidal water dispersible granules containing 3-chloro-N-(3-chloro-5-trifluoromethyl-2-pyridyl)-2,6-dinitro-4-trifluorom ethylbenzene and optionally other fungicidal compounds including dimethomorph.
However, until now it has not been known that the compounds of formula I with N-pyridylaniline compounds, when admixed in a tank mix or when co-formulated, would show synergistic effects. Moreover, it has not been known that a liquid concentrated composition comprising a synergistic mixture of these compounds can be advantageously be used for controlling diseases caused by oomycetes, e.g. Phytophtora infestans.
A mixture of fungicides shows synergistic effect if the fungicidal activity of the mixture is larger than the sum of activities of the separately applied compounds. The expected fungicidal activity for a given mixture of two fungicides can be calculated as follows (See Colby, S.R., "Calculating synergistic and antagonistic response of herbicide combinations", Weeds 15, pp 20-22 (1967): EQU EE=x+y-x.multidot.y/100
wherein
x is the efficacy in % compared with an untreated control upon treatment with a fungicidal active ingredient A at a dose rate a; PA1 y is the efficacy in % compared with an untreated control upon treatment with a fungicidal active ingredient B at a dose rate b; PA1 EE is the expected efficacy with a combination of fungicidal active ingredients A and B at a dose of a+b, respectively. PA1 (a) at least one acrylic acid morpholide of formula I ##STR2## in which R.sup.1 and R.sup.2 each independently represent hydrogen or halogen atom or an optionally substituted alkyl, alkoxy, alkenyl, alkynyl, alkadienyl, aryl, aryloxy, heteroaryl, cycloalkyl, cycloalkenyl, bicycloalkyl or heterocyclyl group, PA1 (b) and at least one fungicidal N-pyridylaniline compound.
If the actual efficacy (E) exceeds the expected (calculated) one (EE), the mixture displays a synergistic effect.